I've always wondered that myself. Does it really save space going upward? One could argue against that. I've applied RainX on mine and it works really well so far. No complains so far. However, did you notice that when you fold the mirrors the driver's side is slightly slower than the passenger's side? Maybe I've got too much time on my hands, but it's starting to really annoy me. The passenger's side is almost a full second (or half) quicker than the driver's side on mine.

The side mirrors when folded, are rotated inward and upward. Perhaps keeping the mirrors as close as possible to the vehicle.But the upward position easily smear by raindrops,giving the drivers a poor vision when they are unfolded. I have applied water repellent on it, and will see how it works.